Free-grab device for collecting underwater samples

ABSTRACT

A free-grab device for collecting underwater samples. This device comprises a box-like frame, the bottom and two side faces of which are covered at least partially by an orificed wall, the other side faces being uncovered; two similar pick-up jaws which are fitted with scraping blades and which are pivoted on said frame to be displaceable between an open position in which they extend generally towards one another and a closed position in which they are in effective engagement with the uncovered side faces of the frame; return means acting on said jaws to urge them outwardly of said open position towards said closed position; releasable locking means acting on said jaws to lock them in said open position; and release means acting on said locking means to free said jaws when the device touches the seabed.

United States Patent [191 Rossfelder [451 May 27, 1975 FREE-CRAB DEVICEFOR COLLECTING UNDERWATER SAMPLES Inventor: Andre Rossfelder, La Jolla,Calif.

Assignees: Le Nickel; Centre National pour lExploitation des Oceans,both of Paris, France; Tetra Tech Incorporated, Rosemead, Calif. partinterest to each Filed: July 17, 1973 Appl. No.: 379,940

Foreign Application Priority Data July 19, 1972 France 72.26061 U.S. Cl.73/4252 Int. Cl. G01n 1/08 Field of Search 73/425, 425.2; 294/66References Cited UNITED STATES PATENTS 5 /1970 Blair 73/4252 3,572,1293/1971 Walthier et al. 73/4252 Primary ExaminerS. Clement SwisherAttorney, Agent, or Firm-Fleit & Jacobson [57] ABSTRACT A free-grabdevice for collecting underwater samples.

This device comprises a box-like frame, the bottom and two side faces ofwhich are covered at least partially by an orificed wall, the otherside'faces being uncovered; two similar pick-up jaws which are fittedwith scraping blades and which are pivoted on said frame to bedisplaceable between an open position in which they extend generallytowards one another and a closed position in which they are in effectiveengagement with the uncovered side faces of the frame; return meansacting on said jaws to urge them outwardly of said open position towardssaid closed position; releasable locking means acting on said jaws tolock them in said open position; and release means acting on saidlocking means to free said jaws when the device touches the sea-bed.

7 Claims, 1 Drawing Figure 1 I :1 r v 1 l l I F 24 14 25 F FREE-GRABDEVICE FOR COLLECTING UNDERWATER SAMPLES The present invention relatesto a free-grab device for collecting underwater samples, particularlypolymetallic nodules deposited on ocean beds, sometimes at very greatdepths which may be as much as 6,000

metres.

It is known that the expression free-grab device" is used to designatesampling equipment which, in contrast to dredges, is released at thesurface of the water without being connected to a ship or to a fixedsurface installation. The free-grab device is caused to sink by aballast which overcomes the action of one or more floats; when thedevice touches the seabed it releases the ballast automatically and,under float action, rises to the sea surface where it is recovered andwhere the samples contained are removed.

Known free-grab devices are of a form generally similar to that of thegrab-buckets used in civil engineering operations on land, and a deviceof this known kind is disclosed in U.S. Pat. No. 3,572,129. These knowndevices suffer from a certain number of disadvantages. One disadvantageis that the jaws of the bucket often jam in a partly-closed position ontouching the sea-bed, and this can allow most of the collected samplesto escape. Furthermore, the ballast is cast off by means of acomplicated mechanism which is not very reliable in operation.

One of the objects of the present invention is therefore to provide afree-grab device which enables a large quantity of samples to becollected in a single operation carried out in a reliable manner.

A further object of the invention is to provide a freegrab device whichenables the ballast to be cast off in a simple and reliable manner.

Yet another object of the invention is to provide a free-grab devicewhich is of simple construction and inexpensive to produce,

According to the present invention there is provided a free-grab devicefor collecting underwater samples, the device comprising a box-likeframe, the bottom and two side faces of which are covered at leastpartially by an orificed wall, the other side faces being uncovered; twosimilar pick-up jaws which are fitted with scraping blades and which arepivoted on said frame to be displaceable between an open position inwhich they extend generally towards one another and a closed position inwhich they are in effective engagement with the uncovered side faces ofthe frame; return means acting on said jaws to urge them outwardly ofsaid open position towards said closed position; releasable lockingmeans acting on said jaws to lock them in said open position; andrelease means acting on said locking means to free said arms when thedevice touches the sea-bed.

Each of said jaws preferably comprises a cutting blade mounted betweentwo walls pivoted on said frame, said jaws being covered at leastpartially byan orificed wall.

Said orificed walls advantageously comprise a net, the edges of whichare secured to said frame and to said jaws.

Said resilient return means may comprise two resilient loops stretchedbetween said jaws and passing over members secured to said frame.

Said means for locking the jaws preferably comprise two substantiallynon-resilient cables each of which is secured by its ends to said jawson the same side of the sampling device, and the two cables beinginterconnected at their mid zones at the upper part of the device bymeans of a releasable connecting member, The means for releasing thejaws may be a casting-off device of the kind described in our U.S. Pat.application Ser. No. 379,939 filed on July 17, 1973.

The device of the present invention may also include a resilient cradlemounted on said frame to hold ballast in position.

When said jaws are in the open position, they are preferably at an angleof the order of to one another, said cutting blades then beingsubstantially contiguous.

It will be appreciated from the foregoing that the jaws of the samplingdevice pivot outwardly during the pick up operation, and this eliminatesor at least minimises the risk of their becoming jammed on the sea-bedor jammed as a result of samples becoming jammed between the cuttingblades. Also, if one jaw were to be jammed, the other should still beeffective.

The ballast is cast off in a simple and reliable manner, since it isreleased downwardly between the jaws when they pivot outwardly.

An embodiment ofthefpresent invention will now be described, by way ofexample, with reference to the accompanying drawing which is adiagrammatic elevation, partly in section, of a free-grab device inaccordance with the invention.

It should be pointed out for the purpose of clarity, that the free-grabdevice of the present invention will first be described in the positionwhich it occupies upon completion of its descent to the sea-bed tocollect samples, but just before it actually touches the sea-bed so thatit is still in the-open position. Furthermore, expres sions such as,upper and lower which will be used hereinafter, all relate to thepositions of the various elements of the device onthe assumption thatthe device descends vertically towards the sea-bed prior to the actualcollecting operation. Furthermore, these expressions correspond to'thedisposition of the device that has been adopted for, the purpose of thedrawing, so that they will be clearly understood.

As can be seen from the drawing, the device of the invention includes abox-like frame 1 which is constructed of, for example, U-section memberswelded together to form upper and lower sub-frames 2 and 3 which areinterconnectedby vertical members 4a, 4b.

Two similar jaws 5 and 6 are pivoted about shafts 7 and 8, respectively,which are secured to the frame 1 and each of which is located close to ashort end of the lower sub-frame 3. The shafts 7 and 8 are substantiallyparallel to the short ends of the sub-frame 3.

The jaw 5 has a cutting blade 9 which extends between the end parts oftwo vertical walls 10. Near their other end parts, within the frame,each wall 10 which is in the form of an elongated plate disposed nearthe side of the frame 1, is formed with a hole for receiving the shaft7.

The jaw 6 has two walls 12 pivotally mounted on the The faces of jaws 5and 6, and of the lower sub-frame 3, and the two long side faces of themain frame 1, are covered by a net, such as conventional fishing net,the size of the net openings depending on the particlesize of thesediments that are to be collected. Each of these faces can be coveredby a separate piece of net, of rectangular form, the edges of the piecesbeing secured along the elements defining the face. Thus, for example,the piece of net covering the jaw 5 could extend between the walls 10,the blade 9, and the adjacent short side of the lower sub-frame 3.However, for reasons of simplicity and for other reasons that will beexplained hereinafter, it is advantageous to use a single piece of net17 to cover all of these faces. The form of this piece of net 17 can bereadily determined; it suffices for this purpose to imagine that thejaws 5 and 6 and the long side faces 15 of the frame 1 as being turnedoutwardly to lie in the plane of the lower subframe 3. There is thenobtained a cruciform area which provides the required shape, afterincreasing its size to give the form of a pocket. Only the edges of thenet 17 are secured to the device. Starting, for example, from the blade9 and using terminology governed by the disposition of the variouselements as seen in the drawing, the net is secured to the elements inthe following order: along the blade 9, then along the rear wall 10, therear left-hand vertical member 4a of the frame, the rear edge of theupper sub-frame 2, the rear right-hand vertical member 4b, the rear wall12 ofjaw 6, the blade 14, the front wall 12, the front right-handvertical member 4b of the frame, the front edge of the upper sub-frame2, the front left-hand vertical member 4a of the frame, and, finally,the front wall 10 of the jaw 5.

I Before the description of the mode of operation of the device of theinvention, it is to be noted that, if the jaws 5 and 6 are caused topivot outwardly about the shafts 7 and 8, i.e., in the directions of thearrows F and F respectively, until the jaws move into contact with theshort end faces of the frame 1, a box-like form of net or trap isobtained which is open only at the top and is capable of retainingobjects larger than the openings of the net 17.

The device is fitted with return means which force the jaws 5 and 6 topivot outwardly in a precise manner and to move into contact with theshort end faces of the frame 1. This return means may be constituted bya pair of resilient endless loops 18 which are advantageously made of asynthetic material such as NEO- PRENE. One of the loops 18 is fitted atthe front of the device and the other at its rear, and each loop passesover two pulleys 19 and 20 mounted on the wall 10 of the jaw 5 and onthe wall 12 of the jaw 6, respectively. Between these pulleys, the twostrands of each loop pass on theexterior over sleeves 7a and 8a mounted,respectively, on the pivot shafts 7 and 8 of the jaws 5 and 6 and, atthe top of the device, these strands pass over two transverse bars 21and 22 secured to the upper sub-frame 2 of the main frame 1. The lengthof the resilient loops 18 is, of course, such that they are firmlytensioned when fitted so that they apply to the jaws 5 and 6 a couplewhich tends to cause the jaws to pivot outwardly about the shafts 7 and8 and also urge the jaws 5 and 6 firmly against the frame 1 when thedevice is in the closed position.

It will be appreciated that, if it is desired to hold the device intheopen position, that is to say in the position illustrated in thedrawing or in other words ready for collecting a sample, it is necessaryfor a counterforce to oppose the outward return action of the resilientloops 18. This function is performed by two virtually non-resilientcables 23 which apply, one at the front and the other at the rear, anupward pull to the jaws 5 and 6 so as to keep them in position. The twoends of the front cable 23 are thus fixed, one at 24 at the lower end ofthe front wall 10 of the jaw 5, and the other at 25 at the correspondingpoint on the front wall 12 of the jaw 6. The lengths of the cables 23are such that, if the front cable is held at its mid point and passedover the front edge of the upper sub-frame 2 of the main frame 1 andhorizontally in the rearward direction, its mid point comessubstantially into contact with the mid point of the similar cable 23extending from the rear part of the device. It then suffices to connectthe two cables firmly together for example by means of shackles 26connected by a releasable means (not illustrated) in order to lock thejaws 5 and 6 in the open position.

Finally, a resilient cradle is formed by two loops 28, made of, forexample, NEOPRENE, which are stretched between two transverse bars 29and 30 secured to the lower sub-frame 3 of the main frame 1. The purposeof this cradle is to carry a cylindrical ballast element, showndiagrammatically at 31, when the device is in the inverted position aswill be described later.

The operation of the device will now be described, and for this purposeit will be supposed that it is initially in the closed position as, forexample, when it has been recovered and emptied after having collectedsample material.

First, the device is mounted on a rigid frame to enable it to be readyfor use more easily, but inverted so that the sub-frame 2 which is inthe upper position in the drawing is located at the bottom. The ballast31 is placed in the resilient cradle 28, the space enclosed by the net17, in its form described above, being employed for this purpose. Thejaws 5 and'6 are then pivoted inwardly against the action of theresilient loops 18. This operation, which may be facilitated by the useof two similar levers bearing against the sleeves 7a and 8a, iscompleted when the jaws 5 and 6 have moved so that the blades 9 and 14abut against one another. The device may then be temporarily locked bypassing a U- shaped pin 32 into holes 33 formed in the jaws 5 and 6. a

The device is then reinverted to bring it to its normal operatingposition and is lowered into the sea. The ballast 31 now rests on thewalls 10 and 12 of the jaws 5 and 6, and can be cast off after automaticrelease means, which have replaced the U-shaped pin 32, disconnect thecables 23 When the device touches the seabed. When this occurs, the jaws5 and 6 swing outwardly, the blades 9 and 14 scraping the sea-bed, andthe sedimentary material that is to be sampled is moved by the net whichcovers the jaws. The material is trapped in the device when the jawsabut against the small side-faces of the frame. The ballast 31 isdeposited on the sea-bed, and is generally not recoverable.

After the free-grab device has returned to the surface, the net or trapformed by the device is emptied, and the cycle can be repeated.

The metallic parts of the device according to the invention arepreferably made of an aluminium alloy resistant to corrosion by water,for example certain alloys of aluminium and magnesium.

What we claim is:

l A free-grab device for collecting underwater samples, the devicecomprising a box-like frame, the bottom and two side faces of which arecovered at least partially by an orificed wall, the other side facesbeing uncovered; two similar pick-up jaws which are fitted withscrapingblades and which are pivoted on said frame to be displaceablebetween an open position in which they extend generally towards oneanother and a closed position in which they are in effective engagementwith the uncovered side faces of the frame; return means acting on saidjaws to urge them outwardly of said open position towards said closedposition; releasable locking means acting on said jaws to lock them insaid open position; and release means acting on said locking means tofree said jaws when the device touches the sea-bed.

2. A free-grab device according to claim 1, in which each of said jawscomprises a cutting blade mounted between two walls pivoted on saidframe, said jaws being covered at least partially by an orificed wall.

3. A free-grab device according to claim 1, in which said orificiedwalls comprise net, the edges of which are secured to said frame and tosaid jaws.

4. A free-grab device according to claim 1, in which said return meanscomprise two resilient loops stretched between said jaws and passingover members secured to said frame.

5. A free-grab device according claim 1, in which said locking meanscomprise two substantially nonresilient cables each of which is securedby its end to said jaws on the same side of the sampling device, and thetwo cables being interconnected at their mid zones at the upper part ofthe device by means of a releasable connecting member.

6. A free'grab device according claim 1, which comprises a releasableballast and a resilient cradle mounted on said frame to hold saidballast in position.

7. A free-grab device according to claim 1, in which said jaws are at anangle of the order of to one another, in said open position of thedevice. the cutting blades then being substantially contiguous

1. A free-grab device for collecting underwater samples, the devicecomprising a box-like frame, the bottom and two side faces of which arecovered at least partially by an orificed wall, the other side facesbeing uncovered; two similar pick-up jaws which are fitted with scrapingblades and which are pivoted on said frame to be displaceable between anopen position in which they extend generally towards one another and aclosed position in which they are in effective engagement with theuncovered side faces of the frame; return means acting on said jaws tourge them outwardly of said open position towards said closed position;releasable locking means acting on said jaws to lock them in said openposition; and release means acting on said locking means to free saidjaws when the device touches the sea-bed.
 2. A free-grab deviceaccording to claim 1, in which each of said jaws comprises a cuttingblade mounted between two walls pivoted on said frame, said jaws beingcovered at least partially by an orificed wall.
 3. A free-grab deviceaccording to claim 1, in which said orificied walls comprise net, theedges of which are secured to said frame and to said jaws.
 4. Afree-grab device according to claim 1, in which said return meanscomprise two resilient loops stretched between said jaws and passingover members secured to said frame.
 5. A free-grab device accordingclaim 1, in which said locking means comprise two substantiallynon-resilient cables each of which is secured by its end to said jaws onthe same side of the sampling device, and the two cables beinginterconnected at their mid zones at the upper part of the device bymeans of a releasable connecting member.
 6. A free-grab device accordingclaim 1, which comprises a releasable ballast and a resilient cradlemounted on said frame to hold said ballast in position.
 7. A free-grabdevice according to claim 1, in which said jaws are at an angle of theorder of 90* to one another, in said open position of the device, thecutting blades then being substantially contiguous.